What does this mean!?

So normally I have a super heavy period, like super plus tampon needs changed every 2-3 hours. This month I thought I was starting my period because I had spotting on the day I was supposed to begin. But I'm 3 days in and it's still barely there. I tested Saturday (now Friday) and had a BFN. My boobs hurt which is not a normal symptom for my period. Is it possible I'm pregnant and tested too soon? Has anyone found out their pregnant due to these symptoms? Super confused!